Five Is Magic Number for Preventing Breast Cancer Recurrence

May 1, 2001 -- Each morning and again at night, Edith Fitts takes a little pill which she hopes will prevent a recurrence of the breast cancer she was treated for four years ago. On the advice of her doctor, Fitts will take the drug tamoxifen for just one more year. The 66-year-old Wheaton, Ill. woman admits it may feel strange to stop.

"Taking tamoxifen is something I can do to improve the odds that my breast cancer won't come back," she tells WebMD. "I know there is no 100% guarantee, but it does feel good to do something."

For more than 20 years, tamoxifen has been used to treat breast cancer, and it is now widely given as a follow-up therapy to prevent the disease from recurring. Like Fitts' doctor, most physicians prescribe tamoxifen therapy for five years after breast cancer surgery, but it has not been clear whether longer treatment further improves survival.

For more about tamoxifen and breast cancer, check out WebMD's Breast Cancer chat board moderated by Randy Gross, RN.

Now updated data from a large National Cancer Institute (NCI) study suggests it does not. A trial designed to evaluate five-year vs. 10-year treatment with tamoxifen found no survival benefit for patients treated for longer than five years. And patients on the longer regimen were twice as likely to develop endometrial cancers as those who stopped therapy after five years. Twelve of the uterine cancers were reported in the 593 women who continued to receive the drug vs. six in the 579 who did not.

"It has been widely demonstrated that women who take tamoxifen are at greater risk for endometrial cancer, but the risk is still quite small," John Bryant, PhD, of the NCI, tells WebMD. "And with yearly gynecological screening, which everyone taking tamoxifen should have, the cancer is detectable and surgically treatable."

The latest data, reported in the May 2 issue of the Journal of the National Cancer Institute, confirm earlier findings from the same group of patients participating in the NCI's Surgical Adjuvant Breast and Bowel Project (NSABP) B-14 study. Those findings, made public in November of 1995, prompted the NCI to issue a clinical alert to notify doctors that more than five years of postsurgical tamoxifen treatment did not appear to be warranted.